The victim was cut to his arms and chest on Friday (October 5) after he was allegedly approached by an unknown suspect close to the Esso petrol station and junction 8 of the motorway at Maidstone.
Kent Police say the incident happened between 11pm and 11.25pm, and that the victim was walking from the Days Inn Hotel near the services.
The suspect is described by police as white, around 6ft and with a stubble and dark clothing.
He is believed to have spoken with an Eastern European accent.
Police were called after the victim made his way back to the hotel and the man was taken to hospital and has since been discharged.
PC Megan Lovelock said: “We are continuing enquiries to establish the full circumstances of this incident which is reported to have been an unprovoked attack.
“Whilst it took place late in the evening, the area is well lit and would have been busy with cars and lorries.
“It is possible people may have videoed the assault on their phones and we are also urging drivers to review dashcams which may contain important footage.”
Anyone with information is asked to call Kent Police on 01622 604100, quoting reference 46/171561/25.
Alternatively, contact Crimestoppers anonymously on 0800 555 111.
